What is the ruling on working in the sale of cosmetics for a beauty center that provides services which may include sections forbidden by Sharia, and is the salary obtained therefrom lawful?

If your work involves selling permissible tools, there is no harm in it, even if some of them are used for impermissible purposes. However, it is not permissible to sell them to someone whom you know will use them for impermissible purposes, based on the Almighty's saying: "And do not cooperate in sin and aggression." As for tools specifically designated for impermissible uses, selling them is not permissible. If one is unaware of the buyer's intention, then selling them the tools is not forbidden.